dawson



2 Sheets-Sheet i.

Patented Mar. 19; 1889.

Witnesses:

N. PETERS. PhnbLilhognpher. Washinglan. n. c.

.(No Model.) 2 Sheets'-Sheet 2. D. R. DAWSON.

OVEREDGE SEWING MACHINE. No. 399,744. Patented Mar. 19, 1889 Fig. 5-

W/f/VFSSES: m VENTOR,

N. PETERS; PhctoLilhomphur, Washlnfl'um D- Q rrn Starts ATENT rrrcn.

DAVID R. DAIVSON, OF DUNDEE, COUNTY OF FORFAR, SCOTLAND.

OVEREDGE SEWING=MACHINE.

SPECIFICATION forming part of Letters Patent No. 399,744, dated March19, 1889.

Application filed August 21, 1888. Serial No. 283,347. (No model.)

of and in connection with the thread-barrel of sewing machines making anoveredge stitch, and having the thread or yarn first laid round a barrelin loops, which are at lowed to pass off the end of the barrel in amanner to givea proper tension to the stitches as they are beingsuccessively tighten ed.

()veredge sewing-machines of the same general construction as that towhich my in vention relates will be found shown and described in theBritish Patents Nos. 3393 of 1874, 2,856 of 1878, and 4,33% of 1885, andalso in the United States Patent No. 294,627, dated March 4, 1884.

In over-edge sewing-machines of the kind referred to the needle, whichis of a helical form or in the form of a circular arc, passes completelythrough the sacking or other ma terial which is being sewed, and alsoround the thread-barrel, laying a loop of the thread or yarn round thebarrel at each circuit. In sewing a seam, during the first part of theoperation, the thread is laid round the barrel without the stitchesbeing tightened in the material; but when almost all the thread has beenthus laid in loops on the barrel, the end of the thread being fixed inthe material, which is being moved along either continuously or step bystep, the loops successively pass oif the end of the barrel and thestitches become successively tightened in the material. The tension ortightness of the stitches depends upon the manner in which the loopspass off the end of the barrel, and it is this part of the sewingoperation which the improved mechanism hereinafter particularlydescribed is designed to effect in a better manner than heretofore.

On an accompanying sheet of explanatory drawings the improved parts areshown, together with a few other parts of the machine.

Figure 1 is a plan, Fig. 2 is a transverse vertical section, and Fig. 3is a sectional front the barrel. Fig. 5 is a diagram, drawn to anenlarged scale, of a part of Fig. 1, and showin g the manner of sewing.

In the drawings the same reference-letters are used to mark the same orlike parts wherever they are repeated.

In carrying out the invention according to one modification the end A ofthe barrel B is constructed of a stepped form-that is to say, with "hortportions 0 D of reduced diameters. The shoulders are rounded, and thesuccessive smaller parts, 0 D, are, b preference, successively narroweror of less extent in the direction of the length of the barrel. Two suchsteps, 0 1), work satisfactorily, but there may be a single step or morethan two. The stepped end A may be in the s me piece with the barrel B;or it may be, as shown, in a separate piece fixed to the barrel and ether of metal or wood or other suitable material, preference being givento a material which does not become rapidly polished by the friction ofthe thread. A plate, E, fixed on the inner end of a rod or movablebracket, F, which is guided upon a fixed bar, G, is pressed against thebarrel end A, and as each loop of thread or yarn approaches the end ofthe barrel it slips off the largest part onto the first step, C, andthen onto the second step, D, and finally passes between the extreme endand the pressing-plate E. The thread or yarn has an action tending tomove the barrel B back or toward the left hand, and its tension whentightening the stitches is in part due to this backward movement of thebarrel, and in part to the resistance opposed to its slipping off theend of the barrel by the pressing-plate E. The barrel end A may be madeentirely solid or without any movable part, and it acts satisfactorilyif made so for some sizes of machine and kinds of sewing.

According to a second modification, however, and which is shown in theaccompanyin g drawings, I combine What is hereinbefore described as thefirst modification with a button or small curved disk, H, fitted in theextreme end of the barrel end A, and pressed outward by a spring, J,which spring allows the button to yield inward when a loop passesbetween it and the pressing-plate E.

grooves in the socket in the barrel end A.

The pressing-plate E is by preference made, as shown, with its centralpart shaped to fit the front of the button H, and with a steplikedepression round the middle part, such depression forming an annulargroove which guides and controls the thread or yarn when entleringbetween the plate and the barrel en The general operation of the machinewill be understood on reference to Fig. 5. The needle in rotating iscontinually carrying the thread through fresh stitch-holes in the cloth(marked 3 4 5 6) and at the same time throwing loops around the barrelB, which loops cannot be tightened until they slip off between the end Dand the pressingplate E. The cloth is being moved to the right, andpartly causesthe tightening by its dragging action. The loop is shown asjust passing between the end D and the pressingplate E. The half of theneXt loop, which lies behind, from 1 to 2, is not indicated, in order toavoid confusion. The needle has a hook-notch near its tail, (not aneye,) and the thread is doubled and folded in, being caught in the hook.The barrel B rotates, and continually moves the loop toward the left,thus assisting in tightening the stitches. The barrel itself movesslowly to the left, but so to drop the loops off at its end somewhatfaster than the rate at which the needle is forming fresh. loops, thedifference corre sponding to the stitches tightened up from 4 to 1.

In combination with either the first or second modification there maybe, and is by preference, fitted in connection with the pressing-plate Eor bar F carrying it one or more ratchet'catches or equivalent devicesto prevent the plate from being pressed outward or toward the right handwhen the thread or yarn passes between it and the barrel end A. Thepressing-plate E is moved toward the left hand by means of a cord, L,which passes round a pulley, M, and thence over a guidepulley, N, to aweight. (Not shown.) The pulley M is fixed on a spindle, having alsofixed on it a fine-toothed ratchet-wheel, P, with which there engages apawl, Q, centered on a fixed bracket. This ratchet-wheel with its pawlallows the weighted cord L to move the pressing-plate E toward the lefthand, so as to follow the barrel A B and maintain against the endthereof a suitable pressure, which may be varied by altering the weightattached to the cord L, but prevents any return movement toward theright hand. \Vhen at the beginning of a fresh seam the barrel A B andpressing-plate E have to be moved toward the right hand, the pawl Q isturned out of gear, it being made with an upwardly-extending horn whichthe attendant worker can conveniently manipulate.

What I claim is- 1. The improved combination of parts, consisting of athread-barrel made with astepped end and with a spring-pressed endbutton, a

pressing-plate shaped centrally to fit the front of the button andwith astep-like depression round the middle part, a movable brack et carryingthe p ressing-plate and guided on afixed bar, a weighted cord actuatingthe pressing-plate, and a ratch et-and-pawl device connected to thepressing-plate, the several parts operating together, substantially asand for the purposes herein set forth.

2. The combination of the thread-barrel, having a stepped end, with thehelical needle of an overedge sewing-machine, a pressingplate, anddevices, substantially as described, to press the said plate up towardthe stepped end of the thread-barrel, all substantially as set forth.

3. The combination of the helical needle of an overedge sewing-machineand athreadbarrel having a stepped end, and a springpressed end button,with a pressing-plate to bear against the said button, all substantiallyas set forth.

4. The combination of the helical needle of an overedge sewing-machineand a threadbarrel having a stepped end, and a springpressed end button,with a pressing-plate having a central step-like depression, as and forthe purpose specified.

5. The combination of the helical needleof an overedge sewing-machineand a threadbarrel having a stepped end, with a pressingplate having acentral step-like depression, as and for the purpose set forth.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

D. R. DAlVSON.

VVitness'es:

EDMUND HUNT, DAVID FERGUSON.

